If you’ve picked up a health book or magazine lately, you know all about calcium’s role in preventing osteoporosis, the brittle-bone disease that inca­pacitates thousands of women (and men) each year. But if scientific studies are any indication, there may be another, more immediate reason to add a calcium supplement to your medicine chest: It may relieve PMS.

In one study, researchers studied the diet of more than 3,000 women over 10 years and found that those who consumed 1,200 milligrams of calcium and 400 IU of vitamin D a day through food had up to a 40 percent less chance of experiencing PMS. And it appears that choosing the low-fat versions of high-calcium foods made a difference. Women who drank 2 per­cent milk or lower had fewer symptoms than women who drank whole milk.